show model in init/list output #189
Description
With #188, a model can be set by the user.
Show the model in the output of the init (text/verbose or json) and list commands.
If the model is not set by the user using the --model flag, the model used will be the one by default for the agent or the one configured in the agent's settings. This won't be displasyed in the output (empty string)
kortex-cli-api/go module needs to be updated for the json output.
In the table output of the list command, change the AGENT column to AGENT/MODEL, and display the agent-name/model-id in the column, for example claude/claude-sonnet-4.5. If the model is not specified, just display the agent name (eg claude)